Caffeine Treatment Promotes Differentiation and Maturation of Hypoxic Oligodendrocytes via Counterbalancing Adenosine 1 Adenosine Receptor-Induced Calcium Overload

BACKGROUND: We aimed to explore the involvement of adenosine 1 adenosine receptor (A1AR) in hypoxia-induced poor differentiation of oligodendrocytes (OLs), and the underlying mechanism of caffeine treatment in hypoxic injuries. MATERIAL/METHODS: Real-time polymerase chain reaction (RT-PCR) was used to assess the alterations of AR expression in cultured hypoxic OLs with or without caffeine treatment. Then, intracellular alterations of Ca(2+) concentrations ([Ca(2+)]) were detected by confocal Fluo-3 imaging. The subsequent changes of myelin related protein expression were determined by western blot and immunofluorescence. RESULTS: Three hours after hypoxia, significantly upregulated expression of A1AR was observed, accompanied with significantly decreased expression of oligodendrocyte transcription factor (Olig2). In addition, either hypoxia stimulation or 100 μM adenosine induced apparent elevation of resting [Ca(2+)] in cultured OLs. However, pretreatment with DPCPX (A1AR selective antagonist) or caffeine abolished the [Ca(2+)] increase, and the subsequent adenosine of high dose induced Ca(2+) activity in developing OLs. Furthermore, caffeine or DPCPX improved the expression MBP and CNPase proteins after hypoxia stimulation, which resulted in the morphological maturation of OLs. CONCLUSIONS: Caffeine treatment exerted protective effects on neonatal hypoxia injuries. It prevented Ca(2+) overload injury, kept Ca(2+) homeostasis in hypoxic developing OLs, and facilitated optimal expression of myelin related proteins by inhibiting A1AR in vitro. This study also provided experimental evidence for clinical application of caffeine in early treatment of neonatal hypoxia, and highlighted the potential significance of A1AR in anti-hypoxic drug discovery.